The use of captured fasteners is known to increase productivity by reducing assembly time during the manufacturing process, for example, when fastening fixed chain guides to an engine block. The time savings is achieved by pre-attaching the fastener(s) to the chain guide or tensioner arm to be later assembled and secured to an engine block, either manually or by the use of robotics. In the absence of sufficient and purposeful external forces, the fastener capturing arrangement serves to retain the fastener in a desired axial position within the bore. Once the fastener has been installed and axially retained to a chain guide or tensioner arm, the assembly can then be shipped or otherwise transported for later attachment to an engine block. Although its primary purpose is to retain the fastener during handling and shipping, the captive fastener arrangement must also allow for selective translational (axial) and rotational movement of the fastener within the bore as would occur during the bolt tightening procedure for securing the assembly to the engine block. And in the specific case of a tensioner arm for an automotive engine camshaft drive, the fastener retaining device must not inhibit free rotation of the tensioner arm about its fixing point during engine operation as required for chain tensioning.
U.S. Patent Re. 36,164 (reissue of U.S. Pat. No. 5,395,194) discloses a bolt retaining apparatus that includes a separate component made from a resilient polymeric material and it is used extensively in many automotive engine applications to retain standard bolts. This prior art device will not permit proper functionality for many shoulder bolt fixing arrangements, however, and it also has the limitation of requiring the retaining device itself to be pre-assembled, thereby limiting overall savings to assembly time and cost.
It is therefore desirable to provide an improved cost-effective fastener retaining apparatus for shoulder bolt applications that integrates retention features to chain guide or chain tensioner arm components in order to increase manufacturing productivity for the installation of nylon chain guide brackets and tensioner arms used in many automotive engines.